Physical, chemical, and biological characteristics of supraglacial pools on a debris-covered glacier in Mt. Gongga, Tibetan Plateau

Authors: FAIR, HEATHER - Kenyon College; Smiley, Peter - Rocky; LIU, QUIAO - Chinese Academy Of Sciences

Submitted to: Arctic, Antarctic, and Alpine Research (AAAR)
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/15/2020
Publication Date: 11/30/2020
Citation: Fair, H., Smiley, P.C., Liu, Q. 2020. Physical, chemical, and biological characteristics of supraglacial pools on a debris-covered glacier in Mt. Gongga, Tibetan Plateau. Arctic, Antarctic, and Alpine Research (AAAR). 52(1):635-649. https://doi.org/10.1080/15230430.2020.1839165.
DOI: https://doi.org/10.1080/15230430.2020.1839165

Interpretive Summary: Cryoconite holes are aquatic habitats found on glaciers worldwide. Information on the physical features, water quality, and invertebrate-habitat relationships within these ephemeral aquatic habitats within debris-covered glaciers is not available. We measured physical and chemical variables and sampled aquatic insects from cryoconite holes the debris-covered glacier in southeastern Tibet over two summers. Our results when compared with the results of others indicated that the sampled cryoconite holes were larger, more physically diverse, and exhibited lower conductivity levels than cryoconite holes from clean glaciers in other parts of the world. We also documented that the sampled cryoconite holes frequently contained aquatic insects (i.e., midges and springtails) that are not common in cryoconite holes of clean glaciers. The abundance of midges was not was not correlated with any measured environmental variable, while the abundance of springtails was correlated with conductivity, ice-to-water surface depth, and the proximity to other cryoconite holes. These novel results highlight the physical and biological uniqueness of cryoconite holes on a debris covered glacier in southeastern Tibet. These results also represent the first documentation of invertebrate-habitat relationships in cryoconite holes on debris-covered glaciers. Our findings will be of much interest to scientists working on glaciers worldwide because they provide new information on how cryoconite holes on debris covered glaciers differ physically and biologically from cryoconite holes on clean glaciers. Our novel results will also be of much interest to those involved with conservation of aquatic biodiversity in Tibet and China because they provide information that can be used to predict changes in water quality and quantity that will impact invertebrate biodiversity within glacier aquatic habitats in Asia. Our results combined with information from other studies from extreme habitat types (cryoconite holes, headwater streams, ephemeral wetlands) that experience cycles of drying and freezing will also be of interest to state agencies, federal agencies, private consulting companies, and non-profits involved with the management of aquatic ecosystems in agricultural watersheds in the United States because they confirm the importance of a combination of chemical, physical, and landscape variables as determinants of invertebrate biodiversity within disturbance prone aquatic habitats.

Technical Abstract: Cryoconite holes are aquatic habitats found on glacier surfaces worldwide. Much of the current understanding of cryoconite holes comes from clean glaciers sprinkled with wind-blown cryoconite. No information is available on the physical, chemical, and biological characteristics of cryoconite holes on debris-covered glaciers that are common in the Himalayan region. We measured physical and chemical variables and sampled invertebrates from 46 cryoconite holes during the summer of 2018 and 2019 on the debris-covered Hailuogou Glacier in southeastern Tibet. Our physical and chemical results when compared with the results of others indicated that the sampled cryoconite holes exhibited a greater diversity of shapes, were larger, and contained larger substrate sizes, greater substrate diversity, and lower conductivity levels than cryoconite holes from clean glaciers. The sampled cryoconite holes frequently contained Chironomidae and Isotomidae, which are macroinvertebrate taxa that are not common in cryoconite holes on clean glaciers. Chironomidae occurrence and abundance was not correlated with any measured environmental variable. The best predictors of Isotomidae and arthropod occurrence and abundance were specific conductivity, ice to water surface depth, and number of cryoconite holes within 5 m. Our novel results highlight the uniqueness of cryoconite holes on a debris covered glacier in southeastern Tibet.